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Model Output Discussions 18z 31/01/2016

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5 minutes ago, wishingforsnow said:

Didn't ECM model January's cold spell better than the GFS overall?

Yes and no.

GFS was right in the aspect of modelling a southern Greenland shortwave. It was wrong in the whole pushover high which actually ended with an undercut.

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1 hour ago, northwestsnow said:

Please ECM dont be teasing us all us snow starved UK coldies.

A very wintry run up north :)

For Scotland that is of course

The rest of the run produces nothing of interest other than rain.In fact looking at the run I fail to see your wintry run at all?

C__Data_Users_DefApps_AppData_INTERNETEXPLORER_Temp_Saved Images_ECM0-240.gif

 

C__Data_Users_DefApps_AppData_INTERNETEXPLORER_Temp_Saved Images_ECM0-120.gif

Edited by winterof79

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5 minutes ago, wishingforsnow said:

Didn't ECM model January's cold spell better than the GFS overall?

Well the UKMO was first to keep higher pressure to the north, the ECM then took over and yes the GFS was eventually the worst as it wanted to end the cold much earlier than the rest.

Those NCEP discussions were for the shorter term upto T96hrs which given what happens afterwards is important but hopefully NCEP in their State forecasts will comment on the pattern towards next weekend.

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1 hour ago, nick sussex said:

News from NCEP re the upstream pattern. The short term discussion mentions a complex pattern setting up with the guidance all over the place.

The ECM 12hrs and its earlier ensemble mean however are generally preferred as they have been more consistent. The UKMO has been mentioned as much faster than this mornings run.

This part of the discussion is crucial:

FINAL PREFERENCE: BLEND OF THE 12Z ECMWF/00Z ECMWF ENSEMBLE MEAN
FORECAST CONFIDENCE: AVERAGE

LOW AMPLITUDE SPLIT FLOW TRACKING THROUGH THE INTERMOUNTAIN WEST
WILL REACH THE CENTER OF THE COUNTRY BY EARLY FRIDAY. MODELS AGREE
THE SOUTHERN MOST SYSTEM SHOULD DOMINATE AS IT GAINS ADDITIONAL
AMPLITUDE OVER THE SOUTHERN U.S. THIS IS THE POINT WHERE THE
GUIDANCE DIVERGE...PRIMARILY WITH TIMING. ON THE MORE PROGRESSIVE
SIDE ARE THE 12Z NAM/GFS AND 12Z GEFS MEAN/06Z GFS-PARALLEL WITH
THE 12Z GFS TRENDING QUICKER DURING THIS CYCLE. THIS BRINGS ITS
SOLUTION OUT AHEAD OF ANY OTHER PIECE OF GUIDANCE. ENSEMBLE
SPAGHETTI PLOTS IN RECENT DAYS HAVE SHOWN THE ECMWF SUITE TO BE
QUITE CONSISTENT WITH THIS PATTERN FAVORING SOMETHING SLOWER AND A
BIT MORE AMPLIFIED. THE 12Z ECMWF HAS MAINTAINED THIS CONSISTENCY
WHILE THE 12Z CMC/UKMET MOVED TOWARD THE FASTER
SIDE...PARTICULARLY THE LATTER. GIVEN THE ASSESSMENT ABOVE...THE
PREFERENCE WILL REMAIN A COMBINATION OF THE 12Z ECMWF/00Z ECMWF
ENSEMBLE MEAN.
 

If you look at the GFS between T72 and T96hrs you'll see its view keeps the northern stream low as the stronger feature, the southern steam low is flatter and runs quickly east at T120hrs, its this which then phases with the deep vorticity near Greenland and deepens rapidly.

The UKMO is a halfway house solution between the ECM and GFS.

 

That takes care of the upstream amplification but I think we have more flies in the ointment than that Nick, the  main one being the development of low pressure South of Greenland instead of the trough clearing further East.

 

Edit.

Sorry Nick misread your post, I see what you saying in last paragraph but still think the vorticity S of greenland is the main player.

We can see that ECM doesn't really develop it, UKMO more so and GFS has a fully mature LP system and the amplification behind becomes a bit of a red herring if that low develops.

ECM/UKMO/GFS 120

ECH1-120.GIF?04-0UN120-21.GIFgfsnh-0-120.png

144 

ECH1-144.GIF?04-0UN144-21.GIFgfsnh-0-144.png

 

As long as that low develops then the pattern for us will flatten because it will raise heights across Northern Europe ahead of it. No chance of low pressure disrupting SE a la ECM with that nice jet profile running SE as it is forced W/NW.

Edited by Mucka

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GFS and ECM doing role reverse today, GFS not showing high pressure nosing out of NE Canada towards western Greenland, and instead does its usual lets just steamroll the atlantic through... ECM has removed its shortwave disturbances to the NW merging with the scandi-UK longwave trough to prevent any colder pattern and instead builds high pressure to our north and enables trough disruption thus a much colder pattern..

Such differences are outside the reliable still, so best to keep an open mind on this one, and expect either to manifest.

I'm doubtful we will see much consistency in the models over the coming days as they struggle with the changes taking place over the Pole and the influence of the strat warming, much to plenty of people's annoyance.

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Yes Mucka its not just the shorter term aspects. That's only one of the problems but if the GFS verifies then I'll be waving the towel ready to throw it! Its a long way back to anything remotely interesting from day ten on the GFS.

The GEFS which looked like improving yesterday have flipped on the 12hrs with the majority having a quick phasing of upstream trough and the deep Atlantic low. However if they're wrong with that quick phasing and more progressive upstream pattern within T168hrs then the rest of what they show won't verify.

I won't however be having too much confidence in the ECMs later output because that's been less than trustworthy this winter!

We'll just have to see in the morning, although a backtrack in tonights GFS 18hrs would be welcome.

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Let's not forget that even the GFS route produces a northerly down the line - the background signals for amplification are really starting to come together.

Whether ECM is taking that too far or not, now that is an important question that's always hard to resolve due to known model bias which is often in play but not always - and probably not that much at just +96 hours range?

This uncertainty upstream is mirrored with our own weather for Monday, ECM still producing a notable squeeze on the isobars across the south, which is in line with UKMO but not GFS which has really toned the feature down due to it becoming disengaged from the upper level divergence (supportive of intensification or at least maintenance) before it reaches our shores.

 

In mid-Jan, the MJO managed to drive a short-lived tropospheric split in the polar vortex, despite a strong stratospheric vortex over Greenland (can only get 10 hPa temps from these archives but they'll suffice):

gfsnh-0-6.png?12 gfsnh-10-6.png?12

So this does seem to be a way in which MJO activity during an El Nino can affect the trop. vortex regardless of what's going on in the stratosphere.

This time around, the split is being suggested with the MJO in phase 4/5 (very close to the borderline). If we look at the composites for these two phases in El Nino years you can sort of see how a split between the U.S./Canada and the UK/Svalbard can be achieved provided there is enough of a high pressure area over Greenland - with transient mid-Atlantic ridging an optional extra.

FebENMJOphase4gt1500mb.gif FebENMJOphase5gt1500mb.gif

The models were recently moving more in line with the phase 4 composite shown above, only to have now trended more toward the phase 5 composite BUT with heights notably lower over Europe. Interestingly this ties in with the typical effects of El Nino forcing that's focused more in the Central Pacific, which is something that we have seen emerge in recent weeks, with a shift in the convective maximum to reflect this. That this has been observed despite SST anomalies still above +1.0*C (but only just!) the Eastern Pacific (NINO 1+2) is truly remarkable.

You can really see the imbalance here, given that the higher the NINO number, the further toward the Dateline it is:

ssta_c.gif

The trends are also unmistakable. By this measure we are seeing the emergence of by far the strongest Central Pacific El Nino on record.

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How can the models be taken seriously!! When they change in 6 to 12hr period, I mean really… its impossible, even the Met are struggling… just a thought

But they keep showing, the Holy Grail… which is what I want lol :D

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Im really surprised today that no one has happened to mention the GEM runs today... 

OK still out in FI but very similar with its morning run.. The 12z miles better than the 00z with heights being pumped up over the pole and heading in towards Greenland.. 

What is of more interest though is the displacing Azores high towards North East canada... 

Heres the 240 profile... but best viewed frame by frame here...  http://www.meteociel.fr/modeles/geme_cartes.php?ech=6&code=0&mode=0&carte=1&archive=0

gemnh-0-240.thumb.png.157cf2e5bc0bea1d7d

I think there is some light at the end of what seems a very long tunnel... and as per usual the GFS isnt interested in a Party just yet ! only at t300 or so does it smell some coffee...

Edited by bryan629

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There are some interesting developments today for coldies. Many runs continue to play with southerly tracking lows and negatively tilted troughs. this could deliver snowfall if we can advect cold air far enough South.  I wonder if the south Welsh hills could be a winter wonderland come next weekend?? 

Anyway, we'll see if this possible Icelandic heights rise gathers any pace in the morning output. 

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33 minutes ago, bryan629 said:

Im really surprised today that no one has happened to mention the GEM runs today... 

OK still out in FI but very similar with its morning run.. The 12z miles better than the 00z with heights being pumped up over the pole and heading in towards Greenland.. 

What is of more interest though is the displacing Azores high towards North East canada... 

Heres the 240 profile... but best viewed frame by frame here...  http://www.meteociel.fr/modeles/geme_cartes.php?ech=6&code=0&mode=0&carte=1&archive=0

gemnh-0-240.thumb.png.157cf2e5bc0bea1d7d

I think there is some light at the end of what seems a very long tunnel... and as per usual the GFS isnt interested in a Party just yet ! only at t300 or so does it smell some coffee...

GFS is always late to the party isn't it? :rofl:

Seriously I really hope the models are onto something and that the ECM continues from this run with UKMO and GFS  following suit preferably. Though as we saw in January, getting cross model agreement can be exhausting to watch at times when picking out developing trends if one model is against another. 

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Looks like a bit of a backtrack from the GFS 18hrs run upstream at T90hrs. Still not the whole way but its a start at least.

Upto T138hrs and its much better than the earlier 12hrs run as it doesn't have that deep low near the UK.

Edited by nick sussex

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7 minutes ago, bluearmy said:

There are some interesting developments today for coldies. Many runs continue to play with southerly tracking lows and negatively tilted troughs. this could deliver snowfall if we can advect cold air far enough South.  I wonder if the south Welsh hills could be a winter wonderland come next weekend?? 

Anyway, we'll see if this possible Icelandic heights rise gathers any pace in the morning output. 

Yes, interestingly there have been a few runs such as yesterday's which also had a southerly tracking jetstream with lows running south of the UK before being dropped this morning and picked up again in tonights ECM

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14 minutes ago, nick sussex said:

Looks like a bit of a back track from the GFS 18hrs run upstream at T90hrs. Still not the whole way but its a start at least.

doesnt it normally backtrack slowly across a 24/48 hour period bit by bit until it falls in line... it certainly did in 2013 cold spells...

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Just now, bigsnow said:

doesnt it normally backtrack slowly across a 24/48 hour period bit by bit until it falls in line... it certainly did in 2013 cold spells...

Yes it normally tries to do it slowly hoping that we won't notice! lol The models though seem very jumpy so lets hope it doesn't jump back tomorrow to its 12hrs trend. I don't mind them jumping forward to a much colder solution!

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7 minutes ago, nick sussex said:

Yes it normally tries to do it slowly hoping that we won't notice! lol The models though seem very jumpy so lets hope it doesn't jump back tomorrow to its 12hrs trend. I don't mind them jumping forward to a much colder solution!

Ive seen MJO and SSW mentioned a few times this week and could this be whats making them so skidish?? are they all over the place because they cant pick up these signals and just start throwing out random runs to try and catch up?? i did see Shannon Entropy mentioned at the start of the week..

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What's interesting and perhaps different from the past week or two of model watching since the January cold spell ended is that we're now seeing potential cold outputs closer than the usual 'day 10' which never comes off and is usually binned after a day. But the fact that the jet sinking south has been shown on a few previous runs prior to tonight's is giving me a bit more confidence that perhaps the models are on to something developing as opposed to another 'garden path' situation.

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In the closer timeframe  there is most certainly a trend for the jet to start to dig further south  giving parts of the country a chance of seeing some snowfall. But for me espicially in fi i cant help notice the amount of precipitation thats falling right through low res  most of us would need a ark if that come to fruition.

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15 minutes ago, weirpig said:

In the closer timeframe  there is most certainly a trend for the jet to start to dig further south  giving parts of the country a chance of seeing some snowfall. But for me espicially in fi i cant help notice the amount of precipitation thats falling right through low res  most of us would need a ark if that come to fruition.

I think it could either be snow or freezing rain depending on one's location 

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Just hope the models are underplaying the upper air temps with these better synoptics that are showing up later in the forecast period. There's just no cold anywhere near us to tap into.

ECM gives -6 to -8 850s into Scotland at day 9 and then that dissipates into mild again.

ECM0-216.GIF?04-0

Was pleasantly warm on a lunchtime walk today and I was thinking ahead to summer. Very springlike, it was. I'll get battered down at Longleat Centre Parcs with wind and rain this weekend, no doubt, but difficult to see this winter turning around to anything cold at this stage.

Edited by kumquat

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Interesting 120 hrs fax chart,definite slider potential going forward.

 

fax120s.thumb.gif.abd959a8d395a88ec8e64e

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2 hours ago, BLAST FROM THE PAST said:

Well a quick one for me but something to think about and something to like about what we see.  Models this time haven't shown the promised land and then battled against each other as to will it hold, has it flipped to total mild mush and then do we get a half way house.  What we are seeing is a gradual subtle upgrading day by day.  This is getting very interesting and its NOT await 2nd half of Feb either,

Edit -  had looked at JMA, ECM, UKMOt - just looked at 12z GFS.....ok here we go

 

BFTP

All respect bftp,you said something along the lines a wk or two back.Even maybe more coldest.

Edited by joggs

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